Cadmium and calcium ions' effects on the growth of Pleurotus ostreatus mycelia are related to phosphatidylethanolamine content.

ABSTRACT

Heavy metal Cd2+ can easily be accumulated by fungi, causing significant stress, with the fungal cell membrane being one of the primary targets. However, the understanding of the mechanisms behind this stress remains limited. This study investigated the changes in membrane lipid molecules of Pleurotus ostreatus mycelia under Cd2+ stress and the antagonistic effect of Ca2+ on this stress. Cd2+ in the growth media significantly inhibited mycelial growth, with increasing intensity at higher concentrations. The addition of Ca2+ mitigated this Cd2+-induced growth inhibition. Lipidomic analysis showed that Cd2+ reduced membrane lipid content and altered lipid composition, while Ca2+ counteracted these changes. The effects of both Cd2+ and Ca2+ on lipids are dose dependent and phosphatidylethanolamine appeared most affected. Cd2+ also caused a phosphatidylcholine/phosphatidylethanolamine ratio increase at high concentrations, but Ca2+ helped maintain normal levels. The acyl chain length and unsaturation of lipids remained unaffected, suggesting Cd2+ doesn't alter acyl chain structure of lipids. These findings suggest that Cd2+ may affect the growth of mycelia by inhibiting the synthesis of membrane lipids, particular the synthesis of phosphatidylethanolamine, providing novel insights into the mechanisms of Cd2+ stress in fungi and the role of Ca2+ in mitigating the stress.